The present invention relates to injection molding and die casting systems. In particular, the present invention relates to vacuum blocks and vent blocks used with injection molding and die casting systems.
Injection molding and die casting processes typically incorporate stationary and ejector mold halves, which open and close to define a cavity where the molding or casting material is injected. Stationary mold halves are also known as the fixed-die halves or holder blocks, or cover blocks, and are mounted to stationary platens. In contrast, ejector mold halves, also known as the movable-die halves or holder blocks, are capable of moving relative to the stationary holder blocks for opening and closing the cavity. Ejector mold halves are mounted to ejector platens, which are generally connected to hydraulic actuators for providing the movement.
Vacuum assistance in injection molding and die casting processes has been utilized to varying degrees for optimizing product quality. The general intent of the vacuum is to improve the production of injection molding and die casting by removing gases from within the molding and casting cavities. These improvements include higher surface quality, reduced level of porosity, and greater physical characteristics. Vacuum assistance generally requires the use of a vacuum pump, a vacuum line connecting the pump to the molding or casting cavity, and a means for preventing excess injected material from flowing into the vacuum system. One approach for preventing the flow of the injected material is with an automated or manual valve located along the vacuum line. The purpose of the valve is to stop the flows of the vacuum and the excess material before the excess material enters the vacuum system.
An alternative approach for preventing the flow of the injected material is with gas purging blocks, such as a vacuum block. Vacuum blocks are typically connected to the stationary and ejector holder blocks, and simultaneously provide a path for allowing the vacuum to remove the gases, and allow the injected material to solidify during the pulling of the vacuum. The solidified material functions as a stopper, preventing further material from flowing into the vacuum system. As such, vacuum blocks preclude the need for mechanical valves.
Similarly, vent blocks allow gases to be purged from the cavity of a molding or casting system. The gases are forced out by the force of the injected material. If the injected material is not stopped, it will continue to flow out with the purged gas. The vent block also allows the injected material to solidify during the injection process, effectively stoppering the purging passageway. Typically, with both vacuum blocks and vent blocks, the excess material that is solidified in the blocks is cut from the molded products and recycled back into the raw materials for further use.
Based upon the molding or casting process required, different vacuum blocks or vent blocks may be required. For example, if a molding or casting system requires vacuum blocks with different cooling properties to produce different products, multiple vacuum blocks may be required. This can become expensive and time consuming if the molding or casting system requires individualized modifications to accommodate each vacuum block. As such, there is a need in the industry for vacuum blocks and vent blocks that are universal in nature, being versatile, efficient, and interchangeable for reducing costs and time.